Just how old is Michigan? Michigan has a long geologic history. The oldest rocks in the state are over 3.5 billion years old. The older rocks in the state host important deposits of iron and copper.

Those resources include the Michigan Geological Repository for Research and Education ... help prioritize the survey's next mapping areas of focus. "We don't need to map the whole state," Yellich says ...

Low-level helicopter flights are planned over areas of Upper Michigan and northern Wisconsin to image geology using airborne ...